This disclosure relates in general to chemical, biological, radiation and explosive detection and, but not by way of limitation, to smartcard detection in a system.
Detection of trace particles or emanations from compounds which may represent a threat to the public is based on the capture and analysis of the material. Capture may be accomplished through contact (e.g., wipe a surface or contact with a capture surface) or through capture from the atmosphere (e.g., forced air flow such as a “puffer” to dislodge particles from surfaces or through vapor sampling from the atmosphere).
Analysis in most current systems employs ion mobility spectroscopy as the mechanism for detecting items of interest. The detection capture and analysis devices may be installed in the infrastructure being protected such as at the portals for entry or exit, positioned to capture from the persons involved through contact (e.g., touch or swipe) or may be handheld and employed by those protecting the infrastructure. Such devices are common in airports today. The devices typically are slow in the capture and analysis process, frequently require operator participation and require regular cleaning, potentially after each use. In addition, the analysis results are frequently ambiguous, resulting in high false alarm rates.
An emerging class of detection devices relies on the capture of the threat indicating material causing a change in the composition of the material of the device which captures it. The change is then observable or causes a detectable change in the reflective photo luminescence. For example, film tags are used in nuclear facilities to determine if there has been exposure to radiation. Optical scanners may be employed to detect the change in luminescence when the capture material is presented. In cases where the change in the capture material is visible, the holder may dispose of the device before the capture event is recorded.
A number of detection technologies/systems exist in the marketplace, the majority of which are focused on explosives. The most publicized are the radio frequency based systems used by the military to detect improvised explosive devices (IEDs) and land mines at stand-off ranges, e.g. terahertz and magnetic resonance technologies. Vapor and particulate detection technologies are used in airports to screen airline passengers. Battery powered hand held sniffer devices are used by the military to screen individuals and suspected bomb making areas for detecting explosives. Most of the above systems are manually operated and/or monitored so as to evaluate each individual or situation being scanned at the time of interrogations.
There is central management of transit systems. Stations can be closed down when overcrowded. Sensors can determine the number of people likely to be on platforms. When crowds reach dangerous levels, access to the station can be shut down. Once crowds dissipate by boarding trains, the entry portals can be opened again.